Face Selection Masking for Painting overlaped by the texture
I'm sorry, but since the Blender 2.73 version release you can't display the wire outlines while painting. 



''Paint mask selection now only shows selection boundary (so you can better see what you are painting)'', as you can read in this manual: http://wiki.blender.org/index.php/Dev:Ref/Release_Notes/2.73/Painting